1. Field of the Invention
The present invention relates to a film conveying apparatus used in an image recording apparatus or the like and, more specifically, to a film conveying apparatus having an optical slack detecting apparatus.
2. Description of the Related Art
A conventional film conveying apparatus used in an image recording apparatus and the like employs a slack detector for detecting a slack of the film, and driving of the film conveying means is controlled by signals from the detector, in order to maintain appropriate slacking of the film. The film slack detector mainly comprises a light emitting apparatus such as a light emitting diode and a light receiving apparatus receiving light therefrom, and the slack of the film is detected by interception of light by the film.
In the film conveying apparatus, the slack detecting apparatus is almost always in operation so as to detect the slack of the film. Consequently, the light from the light emitting apparatus almost always irradiates the film. Although the light from the light emitting apparatus has a wavelength to which the film is not very sensitive, it is possible that the film is affected by the exposure for long period of time.